The present invention relates to pharmaceuticals and, more particularly, it relates to novel amide derivatives or salts thereof and also to therapeutic agents for diabetes mellitus containing them as effective components.
Diabetes mellitus is a disease accompanied by continuous hyperglycemic state and is said to be resulted by action of many environmental factors and genetic factors. The main controlling factor for blood sugar is insulin, and it has been known that hyperglycemia is resulted by deficiency of insulin or by excess of factors which inhibit its action (such as genetic cause, lack of exercise, obesity and stress).
Diabetes mellitus is classified into two main types. One is insulin-dependent diabetes mellitus (IDDM) caused by a lowering of insulin-secreting function of pancreas due to autoimmune diseases, and another is non-insulin-dependent diabetes mellitus (NIDDM), caused by a lowering of insulin-secreting function of pancrease due to pancreatic fatigue accompanied by continuous high insulin secretion. 95% or more of diabetic patients in Japan are said to suffer from NIDDM, and an increase in the patients due to a change in daily life style is becoming a problem.
As to the therapy of diabetes mellitus, dietetic treatment, therapeutic exercise and remedy of obesity are mainly conducted in mild cases while, when the disease progresses, oral antidiabetic drugs (for example, insulin secretion promoters such as sulfonylurea compounds and insulin sensitivity potentiators which potentiate the sensitivity of insulin) are administered. In severe cases, an insulin preparation is administered. However, there has been a brisk demand for creation of the drugs whereby higher control for blood sugar is possible, and development of antidiabetic drugs having a new mechanism and having high usefulness has been demanded.
U.S. Pat. Nos. 4,396,627 and 4,478,849 describe phenylethanolamine derivatives and disclose that those compounds are useful as drugs for obesity and for hyperglycemia. Action of those compounds is reported to be due to a stimulating action to xcex23-receptors. Incidentally, it has been known that xcex2-adrenaline receptors are classified into xcex21, xcex22 and xcex23 subtypes, that stimulation of xcex21-receptor causes an increase in heart rate, that stimulation of xcex22-receptor stimulates decomposition of glycogen in muscles, whereby synthesis of glycogen is inhibited, causing an action such as muscular tremor, and that stimulation of xcex23-receptor shows an anti-obesity and an anti-hyperglycemia action (such as decrease in triglyceride, decrease in cholesterol and increase in HDL-cholesterol).
However, those xcex23-agonists also have actions caused by stimulation of xcex21- and xcex22-receptors such as increase in heart rate and muscular tremor, and they have a problem in terms of side effects.
Recently, it was ascertained that xcex2-receptors have differences to species, and it has been reported that even compounds having been confirmed to have a xcex23-receptor selectivity in rodential animals such as rats show an action due to stimulating action to xcex21- and xcex22-receptors in human being. In view of the above, investigations for compounds having a stimulating action which is selective to xcex23-receptor in human being have been conducted recently using human cells or cells where human receptors are expressed. For example, WO 95/29159 describes substituted sulfonamide derivatives represented by the formula set forth below and discloses that due to their selective stimulating action to xcex23-receptors in human being, they are useful against obesity, hyperglycemia, etc. However, this patent does not specifically disclose an insulin secretion promoting action and an insulin sensitivity potentiating action of those compounds. 
(In the formula, the symbols should be referred to in the specification of this patent.)
As such, there has been still a demand for creation of therapeutic agents for diabetes mellitus of a new type which have a highly clinical usefulness.
The present inventors have conducted an intensive investigation on compounds having both an insulin secretion promoting action and an insulin sensitivity potentiating action and found that novel amide derivatives show both a good insulin secretion promoting action and a good insulin sensitivity potentiating action and furthermore show a selective stimulating action to xcex23-receptors, leading to accomplishment of the present invention.
That is, the present invention relates to an amide derivative represented by the general formula (I) set forth below or a salt thereof that is useful for the therapy of diabetes mellitus, having both an insulin secretion promoting action and an insulin sensitivity potentiating action and further having anti-obesity and anti-hyperlipemia actions due to a selective stimulating action to xcex23-receptors. The present invention also relates to a pharmaceutical agent, particularly to a therapeutic agent for diabetes mellitus containing the amide derivative or the salt thereof as an effective ingredient. 
(In the formula, each of the symbols means as follows:
ring B: a heteroaryl group which may be substituted and may be fused with a benzene ring;
X: a bond, lower alkylene or alkenylene which may be substituted with hydroxy or a lower alkyl group, carbonyl, or a group represented by xe2x80x94NHxe2x80x94 (when X is a lower alkylene group which may be substituted with a lower alkyl group, the hydrogen atoms bonded to the carbon atom constituting the ring B may form a lower alkylene group together with the lower alkyl group so that a ring is formed);
A: lower alkylene or a group represented by -lower alkylene-Oxe2x80x94;
R1a, R1b: they may be the same or different and each is a hydrogen atom or a lower alkyl group;
R2: a hydrogen atom or a halogen atom; and
Z: a nitrogen atom or a group represented by xe2x95x90CHxe2x80x94.)
The compound of the general formula (I) is further illustrated as follows.
In the definitions used in the general formula in this specification, the term xe2x80x9clowerxe2x80x9d means a linear or branched hydrocarbon chain having from 1 to 6 carbon atoms unless otherwise specified.
Specific examples of the xe2x80x9clower alkyl groupxe2x80x9d are methyl, ethyl, and linear or branched propyl, butyl, pentyl and hexyl, preferably an alkyl having from 1 to 4 carbon atoms, and particularly preferably methyl, ethyl, propyl and isopropyl.
Examples of the xe2x80x9clower alkylene groupxe2x80x9d is a divalent group obtained by removing an arbitrary hydrogen atom(s) from the above xe2x80x9clower alkyl groupxe2x80x9d, preferably an alkylene group having from 1 to 4 carbon atoms, and particularly preferably methylene, ethylene, propylene and butylene. Examples of the xe2x80x9clower alkenylene groupxe2x80x9d are vinylene, propenylene, butenylene, pentenylene and hexenylene groups.
The xe2x80x9cheteroaryl group which may be fused with a benzene ringxe2x80x9d in the xe2x80x9cheteroaryl group which may be substituted and may be fused with a benzene ringxe2x80x9d means a ring group where a benzene ring is fused with a heteroaryl group as mentioned later or a non-fused heteroaryl group.
Specific examples of the xe2x80x9cring group where the benzene ring is fused with a heteroaryl groupxe2x80x9d are fused-ring heteroaryl groups such as quinolyl, isoquinolyl, quinazolinyl, quinolidinyl, quinoxalinyl, cinnolinyl, benzimidazolyl, imidazopyridyl, benzofuranyl, benzoisoxazolyl, benzoxazolyl, benzothiazolyl, oxazolopyridyl, isothiazolopyridyl, benzothienyl, etc.; and oxo-added rings such as oxobenzofurayl, etc.
Examples of the xe2x80x9cheteroaryl groupxe2x80x9d are monocyclic heteroaryl groups such as furyl, thienyl, pyrrolyl, imidazolyl, thiazolyl, pyrazolyl, isothiazolyl, isoxazolyl, pyridyl, pyrimidyl, pyridazinyl, pyrazinyl, thiadiazolyl, triazolyl, tetrazolyl, etc.; and bicyclic heteroaryl groups such as naphthylidinyl, pyridopyrimidinyl, etc.
The substituent in the xe2x80x9cheteroaryl group which may be substituted and may be fused with a benzene ringxe2x80x9d may be any group which can be usually substituted in this ring group. Preferred examples are a halogen atom and lower alkyl, lower alkenyl, lower alkynyl, hydroxy, sulfanyl, halogeno lower alkyl, lower alkyl-Oxe2x80x94, lower alkyl-Sxe2x80x94, lower alkyl-Oxe2x80x94COxe2x80x94, carboxy, sulfonyl, sulfinyl, lower alkyl-SOxe2x80x94, lower alkyl-SO2xe2x80x94, lower alkyl-COxe2x80x94, lower alkyl-COxe2x80x94Oxe2x80x94, carbamoyl, lower alkyl-NHxe2x80x94COxe2x80x94, di-lower alkyl-Nxe2x80x94COxe2x80x94, nitro, cyano, amino, guanidino, lower alkyl-COxe2x80x94NHxe2x80x94, lower alkyl-SO2xe2x80x94NHxe2x80x94, lower alkyl-NHxe2x80x94, di-lower alkyl-Nxe2x80x94, xe2x80x94O-lower alkylene-Oxe2x80x94, etc. These substituents may further be substituted with a substituent such as an aryl group, a heteroaryl group, a halogen atom, hydroxy, sulfanyl, halogeno lower alkyl, lower alkyl-Oxe2x80x94, lower alkyl-Sxe2x80x94, lower alkyl-Oxe2x80x94COxe2x80x94, carboxy, sulfonyl, sulfinyl, lower alkyl-SOxe2x80x94, lower alkyl-SO2xe2x80x94, lower alkyl-COxe2x80x94, lower alkyl-COxe2x80x94Oxe2x80x94, carbamoyl, lower alkyl-NHxe2x80x94COxe2x80x94, di-lower alkyl-Nxe2x80x94COxe2x80x94, nitro, cyano, amino, guanidino, lower alkyl-COxe2x80x94NHxe2x80x94, lower alkyl-SO2xe2x80x94NHxe2x80x94, lower alkyl-NHxe2x80x94, di-lower alkyl-Nxe2x80x94, etc. These substituents such as an aryl group, a heteroaryl group, etc. may further be substituted with a halogen atom, etc.
The xe2x80x9clower alkenyl groupxe2x80x9d is a linear or branched alkenyl group having 2 to 6 carbon atoms, and its specific examples are vinyl, propenyl, butenyl, pentenyl and hexenyl groups.
The xe2x80x9clower alkynyl groupxe2x80x9d is a linear or branched alkynyl group having 2 to 6 carbon atoms, and its specific examples are ethynyl, propynyl, butynyl, pentynyl and hexynyl.
The xe2x80x9chalogen atomxe2x80x9d means a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, and the xe2x80x9chalogeno lower alkyl groupxe2x80x9d means a group where an arbitrary hydrogen atom or atoms in the above-mentioned alkyl group is/are substituted with a halogen atom or atoms.
The case when X is a bond means that a carbon atom of the xe2x80x94COxe2x80x94 group is directly bonded to the ring B.
The compound (I) of the present invention has at least one asymmetric carbon atom and therefore, there are optical isomers such as (R)-compounds, (S)-compounds, etc., racemates, diastereomers, etc. The present invention includes all and each of isolated isomers and mixtures thereof. The present invention also includes hydrates, solvates (such as those with ethanol) and polymorphic substances of the compound (I).
The compound (I) of the present invention may form a salt with an acid. Examples of the salt are acid addition salts with mineral acids such as hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, nitric acid, phosphoric acid, etc.; and those with organic acids such as formic acid, acetic acid, propionic acid, oxalic acid, malonic acid, succinic acid, fumaric aid, maleic acid, lactic acid, malic acid, citric acid, tartaric acid, carbonic acid, picric acid, methanesulfonic acid, ethanesulfonic acid, glutamic acid, etc.
The compound of the present invention or the salt thereof may be manufactured by application of various synthetic methods utilizing the characteristics of its fundamental skeleton or type of the substituent. Representative manufacturing methods are illustrated as hereunder.
First Manufacturing Method 
(In the formulae, R1a, R1b, R2, A, B, X and Z have the same meanings as defined already; Ra is a protective group for amino; and Y1 is a leaving group, and more specifically hydroxy, lower alkoxy or halide.)
In this method, the compound (II) and the compound (III) are subjected to amidation, and the protective group is then removed therefrom to synthesize the compound (I) of the present invention.
The amidation in this manufacturing method can be conducted by customary manners.
The solvent may vary depending upon Y1 of the compound (III) and mostly, an inert solvent or an alcoholic solvent (such as isopropanol, etc.) may be applied.
When Y1 is a hydroxy group, a method where the reaction is conducted in the above-mentioned solvent in the presence of a condensing agent may be applied. Examples of the condensing agent are N,Nxe2x80x2-dicyclohexylcarbodiimide (DCC), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDCI), 1,1xe2x80x2-carbonyldiimidazole (CDI), diphenylphosphoryl azide (DPPA), diethylphosphoryl cyanide (DEPC), etc.
When Y1 is lower alkoxy, a method where the reaction is conducted under heating or refluxing as it is or in the above-mentioned inert solvent may be applied.
When Y1 is halide, a method where the reaction is conducted in the above-mentioned inert solvent in the presence of a base may be applied.
Examples of the inert solvent are dimethylformamide (DMF), dimethylacetamide, tetrachloroethane, dichloromethane, dichloroethane, chloroform, carbon tetrachloride, tetrahydrofuran, dioxane, dimethoxyethane, ethyl acetate, benzene, toluene, xylene, acetonitrile, dimethyl sulfoxide, etc., and mixed solvents thereof, and they may be appropriately selected depending upon each reaction condition. Examples of the base are inorganic bases such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, etc.; and organic bases such as N-methylmorpholine, triethylamine, diisopropylethylamine, pyridine, etc.
The protective group of the amino represented by Ra means a protective group which is commonly used for amino by those skilled in the art, and its representative examples are acyl such as formyl, acetyl, propionyl, methoxyacetyl, methoxypropionyl, benzoyl, thienylacetyl, thiazolylacetyl, tetrazolylacetyl, thiazolylglyoxyloyl, thienylglyoxyloyl, etc.; lower alkoxycarbonyl such as methoxycarbonyl, ethoxycarbonyl, tert-butoxycarbonyl, etc.; aralkyloxy-carbonyl such as benzyloxycarbonyl, p-nitrobenzyloxycarbonyl, etc.; lower alkanesulfonyl such as methanesulfonyl, ethanesulfonyl, etc.; aralkyl such as benzyl, p-nitrobenzyl, benzhydryl, trityl, etc.; tri-(lower alkyl)silyl such as trimethylsilyl, etc.; and the like.
Removal of the protective group in this manufacturing method may be conducted by customary manners. For example, the protective group for amino represented by Ra may be easily removed, for example, by i) a method where in case that the protective group is benzhydryl, p-methoxybenzyl, trityl, tert-butoxycarbonyl, formyl, etc., treatment with an acid such as formic acid, trifluoroacetic acid, a trifluoroacetic acid-anisole mixed solution, a hydrobromic acid-acetic acid mixed solution, a hydrochloric acid-dioxane mixed solution, etc. is conducted; ii) a method where in case that the protective group is benzyl, p-nitrobenzyl, benzhydryl, trityl, etc., a catalytic reduction method using palladium-carbon or palladium hydroxide-carbon is conducted; and iii) a method where in case that the protective group is a tri-(lower alkyl) silyl or the like, treatment with water, fluoride anion (e.g., tetra-n-butylammonium fluoride, sodium fluoride, potassium fluoride, hydrofluoric acid), etc. is conducted.
Second Manufacturing Method 
(In the formulae, R1a, R1b, R2, A, B, X and Z have the same meanings as defined already.)
In this manufacturing method, the compound (IV) is reacted with the compound (V) to give the compound (I) of the present invention.
The amine compound (IV) and the compound (V) are reacted under heating or refluxing for 1 to 24 hours as they are or in an inert solvent, to give the compound (I) of the present invention.
Examples of the inert solvent are acetonitrile, tetrahydrofuran, 2-butanone, dimethyl sulfoxide and N-methylpyrrolidone. In the reaction, a base such as sodium bicarbonate, potassium carbonate or diisopropylethylamine may be added to the reaction mixture.
Incidentally, in the above manufacturing methods, it is possible to purify the resulting substance by removing undesired by-products by means of recrystallization, pulverization, preparative thin layer chromatography, silica gel flash chromatography (as described in W. C. Still, et al., J. Org. Chem., 43, 2923 (1978)), medium-pressure liquid chromatography and HPLC. The compound produced through HPLC can be isolated as a corresponding salt.
The starting material used in the above-mentioned manufacturing methods may be easily manufactured by the methods which are known to those skilled in the art. One of the representative methods is shown as hereunder.

(In the formulae, R1a, R1b, R2, Ra, A and Z have the same meanings as defined already; Rb is a hydrogen atom or an aralkyl-based protective group for amino; and Rc is epoxy, 2-haloacetyl or 1-carboxymethan-1-ol.)
This manufacturing method is composed of from step (a) to step (c) in which the step (a) is a step where the compound (VI) is reacted with the compound (VII), followed by reduction reaction to give the compound (VIIIa) depending upon the type of Rc,; the step (b) is a step where protection is conducted when Rb of the compound (VIIIa) is a hydrogen atom; and the step (c) is a step where nitro is reduced to amino to give the compound (II).
Examples of the aralkyl-based protective group for amino used in this manufacturing method are benzyl, p-nitrobenzyl, benzhydryl, etc.
Step (a)
Illustration is made for the following three cases.
1) When Rc is epoxy, the compound (VI) may be reacted with the compound (VII) by the same manner as in the above-mentioned second manufacturing method. Reaction conditions such as reaction temperature, solvent, etc. are the same as well.
2) When Rc is 2-haloacetyl, the compound (VI) is reacted with the compound (VII) in the presence of a base, followed by reduction reaction to prepare the compound (VIIIa). The base is the same as that mentioned in the first manufacturing method. The reduction reaction may be conducted in the above-mentioned inert solvent or in a solvent of an alcohol type with stirring in the presence of a reducing agent. Examples of the reducing agent are sodium borohydride, sodium cyanoborohydride, lithium aluminum hydride, borane, etc.
3) When Rc is 1-carboxymethan-1-ol, the compound (VI) is reacted with the compound (VII) in the presence of a condensing agent, followed by reduction reaction in the same manner as in 2) to prepare the compound (VIIIa). The condensing agent is the same as that mentioned in the first manufacturing method.
Step (b):
When Rb in the compound (VIIIa) is a hydrogen atom, the amino group is protected by customary manners using di-tert-butyl dicarbonate, etc., to prepare the compound (VIIIa).
Step (c):
A method for the reduction of nitro to amino may be conducted by customary manners such as metallic reduction using iron, zinc, etc. and catalytic reduction using a catalyst such as palladium-carbon, palladium hydroxide-carbon, Raney nickel, etc. Ra becomes a hydrogen atom depending upon the reduction conditions, but it may be protected again by customary manners.

(In the formulae, R1a, R1b, Rb, A, B, X and Y1 have the same meanings as defined already.)
This reaction is a reaction where the compound (IX) and the compound (III) are subjected to amidation reaction to give a compound (IVa) and, when Rb is a protective group for amino, the protective group is removed to give a compound (IV). The amidation reaction can be conducted by the same manner as in the above-mentioned first manufacturing method, and the reaction conditions such as reaction temperature, solvent, etc. are the same as well. 
This reaction is a reaction where the compound (X) and the compound (III) are subjected to amidation reaction and then to reduction reaction to give a compound (IVb). The amidation reaction can be conducted by the same manner as in the above-mentioned first manufacturing method, and the reaction conditions such as reaction temperature, solvent, etc. are the same as well. In the reduction reaction, the above-mentioned catalytic reduction, or a method where reduction is conducted using sodium borohydride in the presence of cobalt chloride, may be applied.
With regard to other compounds such as the compound (III), the compound (V), the compound (VI), and the compound (VII), those which are available in the market or are appropriately synthesized by known methods (such as N-alkylation reaction, cyclization reaction, hydrolysis reaction, etc.) from the commercially available compounds may be used.
The compound (I) of the present invention which is manufactured as such is isolated and purified as a free compound, a salt thereof obtained by means of salt formation by customary manners, a hydrate, a solvate with various solvents such as ethanol, etc., or polymorphic crystals, etc. The isolation and purification may be conducted by applying common chemical operations such as extraction, concentration, evaporation, crystallization, filtration, recrystallization, various chromatographic methods, etc.
Various isomers may be isolated by customary manners utilizing the physico-chemical differences between the isomers. For example, the racemate can be converted to stereochemically pure isomers by common racemic resolution (such as a method where the racemate is changed to diastereomer salts with usual optically active acid (for example, tartaric acid), followed by optical resolution, and the like). Incidentally, a mixture of diastereomers may be separated by customary method such as fractional crystallizaiton or chromatography, etc. In the case of an optically active compound, it may be manufactured starting from an appropriate optically active material.
The phenethanol derivative of the present invention represented by the general formula (I) or the salt thereof has both an insulin secretion promoting action and an insulin sensitivity potentiating action and also has a selective xcex23-receptor stimulating action, so that it is useful as a therapeutic agent for diabetes mellitus.
As confirmed by a glucose tolerance test and a hypoglycemic test in insulin-resisting model animals as described later, the compound of the present invention has both a good insulin secretion promoting action and a good insulin sensitivity potentiating action, so that its usefulness in diabetes mellitus is expected. Although the xcex23-receptor stimulating action may have a possibility of participating in expression of the insulin secretion promoting action and the insulin sensitivity potentiating action, other mechanism might also possibly participate therein, and the details thereof have been still unknown yet. The xcex23-receptor stimulating action of the compound of the present invention is selective to xcex23-receptors in human being. It has been known that the stimulation of xcex23-receptor stimulates decomposition of fat (decomposition of the fat tissue triglyceride into glycerol and free fatty acid), whereby a disappearance of fat mass is promoted. Therefore, the compound of the present invention has an anti-obesity action and an anti-hyperlipemia action (such as triglyceride lowering action, cholesterol lowering action and HDL cholesterol increasing action) and is useful as a preventive and therapeutic agent for obesity and hyperlipemia (such as hypertriglyceridemia, hypercholesterolemia and hypo-HDL-lipoproteinemia). Those diseases have been known as animus factors in diabetes mellitus, and amelioration of those diseases is useful for prevention and therapy of diabetes mellitus as well.
The compound of the present invention is also useful as a preventive and therapeutic agent for other diseases where the improvement of symptom can be achieved by reducing the symptoms of obesity and hyperlipemia such as ischemic coronary diseases such as arteriosclerosis, myocardial infarction, angina pectoris, etc. cerebral arteriosclerosis such as cerebral infarction, etc., or aneurysm, etc.
Further, the selective xcex23-receptor stimulating action of the compound of the present invention is useful for prevention and therapy of s several diseases which have been reported to be improved by the stimulation of xcex23-receptor. Examples of those diseases are shown as follows.
It has been mentioned that the xcex23-receptor mediates the motility of non-sphincteral smooth muscle contraction, and because it is believed that the selective xcex23-receptor stimulating action assists the pharmacological control of intestinal motility without being accompanied by cardiovascular action, the compound of the present invention has a possibility of being useful in therapy of the diseases caused by abnormal intestinal motility such as various gastrointestinal diseases including irritable colon syndrome. It is also useful as the therapy for peptic ulcer, esophagitis, gastritis and duodenitis (including that induced by H. pylori), enterelcosis (such as inflammatory intestinal diseases, ulcerative colitis, clonal disease and proctitis).
It is further shown that the xcex23-receptor affects the inhibition of release of neuropeptide of some sensory fibers in lung. The sensory nerve plays an important role in neurogenic inflammation of respiratory tract including cough, and therefore, the specific xcex23-agonist of the present invention is useful in the therapy of neurogenic inflammation and in addition, has little action to cariopulmonary system.
Moreover, the xcex23-adrenaline receptor is capable of resulting in a selective antidepressant action due to stimulation of the xcex23-receptor in brain, and accordingly, the compound of the present invention has a possibility of being useful as an antidepressant.
The action of the compound of the present invention has been ascertained to be selective to xcex23-receptors as a result of experiments using cells expressing human type receptors, and the adverse action caused by other xcex23-receptor stimulation is low or none.
Effects of the compound of the present invention have been ascertained by the following tests.
1. Hypoglycemic Test in kk Mice (insulin-resisting model; Obesity and Hyperglycemia)
Male kk mice (blood sugar level: not lower than 200 mg/dl) were subjected to a measurement of blood sugar level under feeding and then randomly classified into groups. The drug to be tested was compulsorily administered orally or subcutaneously once daily for four days, and the blood sugar level after 15 to 18 hours from the final administration was compared with that before the administration (n=6). The blood was collected from a tail vein of the mice using a glass capillary (previously treated with heparin), the protein was removed therefrom, and the amount of glucose in the supernatant liquid (mg/dl) was measured by calorimetric determination by means of a glucose oxidase method. Further, a dose at which the blood sugar level was lowered by 30% as compared with that before the administration with the drug to be tested was expressed as an ED30 value.
As a result, the compound of the present invention significantly lowered the blood sugar level as compared with that before the administration with the drug to be tested in both cases of oral and subcutaneous administrations. In particular, some of the compounds of the present invention exhibited a strong activity so that the ED30 value in the oral administration was 3 mg/kg/day or less. On the other hand, in the above-referenced WO 95/29159, the compound of Example 90 had an ED30 value of 30 mg/kg/day or more, and the compound of Example 92 had an ED30 value of 30 mg/kg/day. From this fact, it has become clear that the compounds of the present invention have a superior potentiating action to insulin sensitivity as compared with those of the above-referenced WO 95/29159.
2. Glucose Tolerance Test in Normal Rats
Male rats of SD strain of seven weeks age were fasted for a whole day and night, then randomly classified into groups and subjected to an oral glucose tolerance test (OGTT) (n+4). The compound to be tested was administered orally or subcutaneously at 30 minutes before administration of glucose (2 g/kg by oral administration). The blood was collected from an abdominal aorta using a heparin-treated glass syringe from the rats which were anesthetized with pentobarbital (65 mg/kg), the protein was removed therefrom, and the amount of glucose in the supernatant liquid (mg/dl) was measured by colorimetric determination by means of a glucose oxidase method. The insulin value in blood was determined by measuring the amount of insulin in plasma (ng/ml) by means of radioimmunoassay (RIA).
As a result, in a group where the compound of the present invention was administered orally or subcutaneously, a significant increase in the insulin value in blood was observed as compared with the group to which no drug was given. An increase in the sugar blood level after administration of glucose was significantly inhibited as well. From those results, it is apparent that the compound of the present invention has a good insulin secretion promoting action and a good hyperglycemia inhibiting action.
3. Stimulating Test to Human xcex23-, xcex22- and xcex21-receptors
Human xcex23-stimulating action was investigated using an SK-N-MC cell system (cells in which human xcex23-receptor and human xcex21-receptor were permanently expressed were purchased) while human xcex22- and xcex21-stimulating actions were investigated using a CHO cell system (cells in which each of human xcex22- and xcex21-receptors was compulsorily expressed were purchased). Stimulating action of the compound (10xe2x88x9210 to 10xe2x88x924 M) were investigated by incubating 105 cells/well of each of the cells on a 24-well plate and checking under a subconfluent state after two days using a producing activity of cyclic AMP (cAMP) as an index. Incidentally, the human xcex23-stimulating action was investigated in the presence of a xcex21-receptor blocker (CGP20712A, 10xe2x88x926 M). Amount of production of cAMP in each cell (pmol/ml) was measured by an RIA method using 125I-cAMP. Intensity of action of each compound was compared by calculating the pD2 value and the maximum activity (I.A. (%) where the maximum reaction of 10xe2x88x926 M isoproterenol was defined as 100%) from the resulting dose-reaction curve.
As a result, it has been ascertained that the compound of the present invention has a selective stimulating action to human xcex23-receptor.
A pharmaceutical composition containing one or more of the compound of the present invention or the salt thereof as an effective ingredient is prepared using common pharmaceutically acceptable vehicles. Administration of the pharmaceutical composition according to the present invention may be either by oral administration or by parenteral administration by, for example, injection, suppository, subcutaneous agent, inhaling agent or intracystic infusion.
The dose may be appropriately decided depending upon each particular case while taking into consideration symptom, age, sex, etc. of the patient but usually, is around 0.01 mg/kg to 100 mg/kg per day for adults in the case of oral administration, and that is administered at a time or by dividing into 2 to 4 times a day. When intravenous injection is conducted depending upon the symptom, the dose is usually around 0.001 mg/kg to 10 mg/kg per day for adults, and that is administered at a time or by dividing into two or more times a day.
With regard to a vehicle for the preparation, nontoxic solid or liquid substances for pharmaceuticals may be used.
Examples of the solid composition for use by means of oral administration according to the present invention are tablets, pills, capsules, diluted powder and granules. In such a solid composition, one or more active substances are mixed with at least one inert excipient such as lactose, mannitol, glucose, hydroxypropyl cellulose, microcrystalline cellulose, starch, polyvinylpyrrolidone, agar, pectin, magnesium metasilicate aluminate and magnesium aluminate. The composition may also contain additives other than the inert excipient such as lubricants such as magnesium stearate; disintegrants such as calcium cellulose glycolate; stabilizers such as lactose; and auxiliary solubilizers such as glutamic acid or aspartic acid by customary manners. Tablets and pills may, if necessary, be coated with sugar coat such as sucrose, gelatin, hydroxypropyl cellulose, hydroxypropylmethyl cellulose phthalate, etc., or with film of gastric or enteric coating substances.
The liquid composition for oral administration includes pharmaceutically acceptable emulsions, solutions, suspensions, syrups and elixirs and contains commonly used inert excipients such as purified water or ethanol. In addition to the inert excipient, the composition may further contain auxiliary agents such as moisturizing or suspending agents, sweeteners, tasting agents, aromatic agents and antiseptic agents. The injection for parenteral administration includes aseptic aqueous or non-aqueous solutions, suspensions and emulsions. The non-aqueous solutions and suspensions include, for example, distilled water for injection and a physiological saline solution. Examples of the solvent for non-aqueous solution and suspension are propylene glycol; polyethylene glycol; plant oils such as cacao butter, olive oil and sesame oil; alcohols such as ethanol; gum arabic; and Polysolvate 80 (trade name). Such a composition may further contain auxiliary agents such as isotonizing agents; antiseptic agents; moisturizing agents; emulsifiers; dispersing agents; stabilizers such as lactose; and auxiliary solubilizers such as glutamic acid and aspartic acid). These may be sterilized, for example, by filtration passing through a bacteria-preserving filter or by compounding of or irradiation with a bactericide. These may also be used by manufacturing a sterile solid composition, followed by dissolving in sterile water or a sterile solvent for injection before use.